Furnace wall construction



Nov. 24, 1931.

c. E. IHAWKE 1,833,677

FURNACE WALL CONSTRUCTION Original Filed'May 2, 1925 2 SheetsSheet 1INVENTOR I 4; A; Zr/M 6W, WW

Nov. 24, 1931. c E. HAWKE FURNACE WALL CONSTRUCTION 1923 2 Sheets-Sheeziginal Filed May 2 INVENTOR Patented Nov. 24, I931 s'mrss T oratorCLARENCE E. HAWKE, OF METUCHIEN, NEW JERSEY, ASSIGNOR TO THE CARBORUNDUMCOMPANY, OF NIAGARA FALLS, NEW

YORK, .A,v CORPORATION OF PENNSYLVANIA FURNACE WALL CON STRUCTIGNApplication filed May 2, 1923, Serial No. 636,146. Renewed October24,1929.

This invention relates to furnace wall constructions, and isparticularly adapted'to be used around the combustion chamber of afurnace. There is a growin tendency to work furnaces at extremely highrates of combustion. Under the increased temperatures resulting fromsuch practice, the setting quickly burns out and when coal is used as afuel, the fused ash reacts with the brickwork and destroys the settingin a very short time. This is especially true with low grade coal, andwhen such fuel is used it is impossible to maintain heavy furnace loadsregularly because of the rapid deterioration of the brickwork.

I overcome this dilficulty by providing a furnace wall lining ofrefractory-material having relatively high heat conductivity and meansfor cooling the back of the material. The preferred material is siliconcarbide. Silicon carbide not only is a very good heat resistingrefractory, but has a relatively high heat conductivity, so that theheat is conducted away from the face of the material which is exposed tothe flame, whereby such viding preheated air for combustion.

In the accompanying drawings, illustrating more or'less diagrammaticallymy invention as applied to a coal-fired furnace.

Figure 1 is a sectional elevation through a furnace taken on the lineII}of Figure 2;

- Figure 2 is a sectional elevation through the furnace taken on theline Ill-11 of Figure 1 g Figure 3 is a section through another t pe offurnace, the air being supplied to the rnace above the grate, and iFigure 4 is a section of the furnace wall on the line lV-IV of Figure 3.0

In the embodiment of my invention illuslow the grate 7 Plates 8 orbrickwork of silicon carbide form the wall between the ducts 3 and theinterior of the furnace, since this material is non-porous, veryrefractory, and possessed of a very high heat conductivity.

In Figures 3 and l, I have illustrated my apparatus as applied toanother type of furnace wherein similar parts have been given the samereference character with the letter a suflixed. In this embodiment aconventional hopper type stoker is illustrated in chain lines andperforated blocks 9 are provided for introducing the air above thegrate. The blocks 9 form a part of the combustion chamber walls and airis preferably supplied to them after it has passed through the air ducts3a behind the refractory plates 8a. Air is supplied tothe ducts So frombelow the grate through an inlet 10 and its direction of travel isclearly indicated by arrows. Ijhave 8a above the perforated tuyereblocks 9 materially improves furnace conditions both from a standpointof operating eificiency and long life.

It will be apparent that in both forms of the invention illustratedthecombustion found that the use of the refractory plates chamber hassilicon carbide walls which not only extend within the zone of the fuelbed, but a substantial distance above such zone. As previously pointedout, when a poor grade of coal is used the fused ash reacts with thebrick Work and destroys the setting in a very short time. This isparticularly true in furnaces under boilers that are highly overrated,it having been found that the brick work above the fuel bed is destroyedprior to that portion in contact with the fuel bed. This results fromthe continual erosion of the side and bridge walls by the flow ofdeposited ash which literally runs down over these walls in a moltencondition; By the present invention I have overcome this difficulty. Theportion of the silicon carbide walls within the zone of the fuel bedismaintained at such a low temperature that clinkers will not adherethereto, while the portion of the silicon carbide walls extending abovethe fuel bed is also cooled so that they are protected fromthe-destructive action of the fluid ash.

The invention has many advantages and 'is particularly valuable wherefurnaces are Worked under severe conditions, such as heavy rating or lowgrade fuel, as it maintains the furnace setting for a long period, withresulting economy in operation and freedom from care.

lVhile I have shown and described certainpreferred embodiments of-myinventionitwill. be understood that the invention is not limited tothese precise embodiments, but that it may be otherwise embodied withinthe scope of the appended claims.

1. In a furnace, a. combustion chamber, said combustion chamber havingside walls and a bridge wall provided with facings of silicon carbide,said silicon carbide facings having many times the thermal conductivityof fire-clay refractory material and extending within the zone of thefuel .bed and a substantial distance above said zone, and a duct back ofsaid facings through which cooling air is circulated in contact with therear Walls of the facings throughout the major portion of the areathereof, a portion of saidfacings above said zone being imperforate, anda portion thereof within's'aid zone being perforate, said ductdelivering to said perforate portion whereby the cooling air whichcirculates through said duct is conducted to walls of the combustionchamber and of many times greater thermal conductivity than fireclayrefractory material, said portions extending both within the zone of thefuel bed and a substantial distance above said zone,

and a duct back of said wall through which cooling air iscirculated inheat conducting relationship to the portions of highthermal conductivityfor cooling said portions to preabove said zone, a. duct back of saidwall through which cooling air 1s circulated in heat conductingrelationship to the portions of'high thermal conductivity for coolingsaid portions to prevent the adherence of clinkcrs thereto, means forsecuring forced circu lation of air through the duct, and means forconducting the preheated air from said duct to the combustion chamber.

In testimony whereof I have hereunto set my hand.

OLA RENCE E. HAWKE.

the fuel bed through said perforate portion in a highly preheatedcondition.

2.,I'n a furnace, .a main wall structure, a combustion chamber definedthereby, said main wall structure having certain portions thereof forminthe walls of the combustion chamber of non-metallic refractory materialof many times greater thermal conductivitv than fire-clayrefractorymaterial,

said portlons extending both within the zone of the fuel bed and asubstantial distance above said zone, and a duct back of said portionsof high thermal conductivity providing an elongated circulating pathcovering substantially the entire area of such portions above the zoneof the fuel bed for cooling the slag in contact with the inner surfacesof said portions to thereby form a protective covering therefor, theportions above the zone of the fuel bed being imperforate.

3. In a furnace, a main wall structure, a combustion chamber definedthereby, said main wall structure having certain portions thereof ofrefractory material forming the

